Using those guidelines, you could create something completely unrecognizable from the source material. What is the themes of Spider-Man? He's a relatable kid dealing with normal problems. Okay, so we'll take that metaphor literally and make Peter a normal kid and turn Soider-Man into a literal school drama. But besides that fact- Marvel DOES use the "facts" of the source material. Hence why Spider-Man wears a red and blue suit ripped directly from the comics, why Steven Strange was a neruo surgeon who injured his hands, why Thor is the son of Odin- why they all retain their original race. The reason why these characters are the way they are is because of the comics. A loose adaption that takes the themes literally and realistically would be something like Josh Trank's F4. Marvel DOES